// 验证当前浏览器是否支持webrtc
// created by @HenrikJoreteg
(function () {

    var prefix;
    var version;

    if (window.mozRTCPeerConnection || navigator.mozGetUserMedia) {
        prefix = 'moz';
        version = parseInt(navigator.userAgent.match(/Firefox\/([0-9]+)\./)[1], 10);
    } else if (window.webkitRTCPeerConnection || navigator.webkitGetUserMedia) {
        prefix = 'webkit';
        version = navigator.userAgent.match(/Chrom(e|ium)/) && parseInt(navigator.userAgent.match(/Chrom(e|ium)\/([0-9]+)\./)[2], 10);
    }

    var PC = window.RTCPeerConnection || window.mozRTCPeerConnection || window.webkitRTCPeerConnection;
    var IceCandidate = window.mozRTCIceCandidate || window.RTCIceCandidate;
    var SessionDescription = window.mozRTCSessionDescription || window.RTCSessionDescription;
    var MediaStream = window.webkitMediaStream || window.MediaStream;
    var screenSharing = window.location.protocol === 'https:' &&
        ((prefix === 'webkit' && version >= 26) ||
            (prefix === 'moz' && version >= 33))
    var AudioContext = window.AudioContext || window.webkitAudioContext;
    var AudioDestination = AudioContext && new AudioContext().createMediaStreamSource && new AudioContext().createMediaStreamDestination
    var videoEl = document.createElement('video');
    var supportVp8 = videoEl && videoEl.canPlayType && videoEl.canPlayType('video/webm; codecs="vp8", vorbis') === "probably";
    var getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.msGetUserMedia || navigator.mozGetUserMedia;

    // export support flags and constructors.prototype && PC
    window.rtcSupport = {
        prefix: prefix,
        browserVersion: version,
        support: !!PC && !!getUserMedia,
        // new support style
        supportRTCPeerConnection: !!PC,
        supportVp8: supportVp8,
        supportGetUserMedia: !!getUserMedia,
        supportDataChannel: !!(PC && PC.prototype && PC.prototype.createDataChannel),
        supportWebAudio: !!(AudioContext && AudioContext.prototype.createMediaStreamSource && AudioDestination),
        supportMediaStream: !!(MediaStream && MediaStream.prototype.removeTrack),
        supportScreenSharing: !!screenSharing,
        // constructors
        AudioContext: AudioContext,
        PeerConnection: PC,
        SessionDescription: SessionDescription,
        IceCandidate: IceCandidate,
        MediaStream: MediaStream,
        getUserMedia: getUserMedia
    };

})()